Along with the rapid growing of economics, energy demand in the industry and our daily life is increasing continuously, while on the other hand the environment protection is facing a tremendous challenge. Since the wind power and hydraulic power are renewable clean power, wind generators and hydraulic generators are more and more applied over the world.
Rotor blades as key elements for driving rotors of wind or hydraulic generators are very important in that their profile and shape are rather decisive to the efficiency of the power generation. For the sake of sufficiently using the energy and increasing the rate of the power transformation, rotors with pitch-variable technology are now the first preference in the market.
Presently, one most commonly used conventional type of pitch-variable rotor is to provide each blade with a separate set of pitch varying mechanism, which is synchronously controlled by one controller. Those types of conventional pitch varying mechanisms usually include a servo motor connected with a gearing transmission, and a direct-driven electric cylinder, etc. However, there are still some deficiencies in the conventional pitch varying mechanisms of the rotors as follows.
Most of those conventional pitch varying mechanisms are designed in a complicated structure with a large size, and therefore not only costly but also not suitable to be installed in small-medium sized generators;
The energy consumption is big due to their multiple driving manner;
The operation reliability is low because a rotary joint must be used for cable connection in all kinds of control circuits in the conventional pitch varying mechanism, and therefore it is difficult to ensure the precision of detection in order to control the operation;
The weight and inertia of the rotor of the generator are both increased because many mechanical parts are accommodated inside of the rotor hub, therefore the rate of failure of the blade varying is increased, and the efficiency of the power generation is reduced;
When a system failure occurs, it is difficult to inspect and repair in a short time in those conventional types of pitch varying mechanism;
An external power supply is indispensable for those conventional pitch varying mechanisms to perform protective blade reinstatement in case of system halt, therefore there is still a risk when this external power supply is failed.
Therefore, it is really desirable to develop a new type of mechanism for synchronously varying pitch of a multi-blade rotor into a simple and compact structure which is easy to be controlled, and with high precision and high operation reliability, but low cost and low energy consumption.